The present invention relates to an electrostatic recording material for use in facsimiles printer and plotters. More particularly, the present invention relates to an electrostatic recording material useful in those facsimiles and plotters which are designed to operate at high speeds with pulse widths ranging from several to several tens of microseconds and which are capable of high resolution of at least 16 lines per millimeter.
The electrostatic recording material consists of an electrically conductive support coated with a recording layer that is formed of a dielectric resin and a pigment. An electrostatic latent image formed by applying voltage to the surface of the recording layer or to both sides of the recording material is developed with a toner which is either in the form of a pigmented powder or a liquid developer. The toner image is then fixed for record production by a suitable means such as the application of heat or pressure or by drying.
With the recent advances in electrostatic recording systems capable of high speed operation at high resolution, production of higher-quality records has been required. One important problem that has remained unsolved is reduced number of dot dropouts that occurs as a result of instable corona-discharge from multi-stylus of electrode. This problem is particularly pronounced with multi-stylus electrostatic recording machines intended for high speed operation at high resolution. It is difficult for a voltage of short pulse width to be accumulated on the styli in the necessary amount to initiate discharging. In addition, the surface areas of the styli in the printhead adapted for high resolution are so small as to reduce the number of areas where voltage concentration occurs and the decreased probability of discharging leads to an increased chance of dot-dropout (i.e., many dots remain unrecorded).
It has been common practice to use pigments in combination with dielectric resins in order to provide gap spaces between the recording layer of an electrostatic recording material and the printhead. Various pigments, both inorganic and organic, have been used or proposed; inorganic pigments include calcium carbonate, talc, titanium dioxide, calcined clay and aluminum oxide, and organics include plastic pigments, starches and fine cellulose powders. However, the use of these pigments has not provided a complete solution to the problem of dot-dropouts. It has therefore been desired to develop an electrostatic recording material that is capable of recording at high resolution and which is substantially free from the problem of dot-dropouts even if it is used with a matrix of styli hving an extremely small diameter at their tip.